The goal of this project is to determine as fully as experimental techniques allow the mechanism(s) by which macromolecules and macromolecular complexes cross the cell membrane. The systems proposed for study are the localization of alkaline phosphatase at the cell surface in E. coli, and the non-lytic release of the filamentous bacteriophage fd. These processes will be studied in bacterial mutants blocked at various steps in the synthesis of lipids in order to assess the role of membrane lipid in these processes. Mutants which have been obtained which are altered in the localization properties of alkaline phosphatase will be studied further to determine whether the alteration prevents transport of the enzyme from the cell. Deletion mutants in which the promoter of the alkaline phosphatase structural gene is fused with the lactose operon will be studied to determine whether the enzyme export mechanism operates at the level of transcription, translation, or on the finished polypeptide. An attempt will be made to isolate mutants blocked specifically in the export of alkaline phosphatase and in the release of phage fd from the cell. Comparative studies will be undertaken with these mutants to ascertain whether enzyme export and phage release share cell components in common.